Palletizer Puller Bar

ABSTRACT

In an item-handling device, a layer head includes an item layer building platform defining an item receiving plane, the layer building platform being vertically positionable. A puller bar mounts to the layer head and moves in relation thereto within a plane above the item-receiving plane. The puller bar is positionable between a retracted position above the layer building platform and an extended position offset from the layer building platform.

RELATED US APPLICATION DATA

This application is a continuation of U.S. application Ser. No.13/587,216, filed Aug. 16, 2012, which is a continuation of U.S.application Ser. No. 12/792,935, filed on Jun. 3, 2010, now U.S. Pat.No. 8,257,011, which is a continuation of U.S. application Ser. No.10/857,590, filed on May 28, 2004, now U.S. Pat. No. 7,736,120, which isa continuation-in-part of U.S. application Ser. No. 10/822,112, filed onApr. 8, 2004, now abandoned, which is a continuation-in-part of U.S.application Ser. No. 09/920,317, filed on Aug. 1, 2001, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates generally to article manipulation devicesand particularly to a palletizing device and method of operation.

Palletizers receive a sequence of items and produce a palletized stackof items. Generally, items are formed into rows, rows formed intolayers, and layers stacked upon a pallet to form a palletized stack ofitems. Thus, a typical palletizer receives a series of items andorganizes the items by row, by layer, and ultimately as a palletizedstack of items on a pallet.

Palletizing calls for efficiency. In many applications, time is mostcritical. A palletizer more efficiently, i.e., more quickly, organizingan incoming series of items into a palletized stack of items representsadvantage in greater production levels, i.e., greater item throughput.

Another important palletizing consideration is size. A more compactmachine takes less floor space and, if necessary, accommodates morepalletizing machines in the same area as would be occupied by relativelylarger palletizing machines. Compact size is, therefore, a desirablefeature in a palletizer.

Accordingly, it would be desirable to provide a palletizer having bothimproved time efficiency and reduced overall size relative toconventional palletizing devices. The subject matter of the presentinvention provides such a palletizer.

SUMMARY OF THE INVENTION

In an item-handling device, a layer head includes an item layer buildingplatform defining an item receiving plane, the layer building platformbeing vertically positionable. A puller bar mounts to the layer head andmoves in relation thereto within a plane above the item-receiving plane.The puller bar is positionable between a retracted position above thelayer building platform and an extended position offset from the layerbuilding platform.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show how the samemay be carried into effect, reference will now be made, by way ofexample, to the accompanying drawings in which:

FIG. 1 illustrates in perspective a synchronized palletizer.

FIG. 2 illustrates in plan view the synchronized palletizer of FIG. 1 astaken along lines 2-2 of FIG. 1.

FIG. 3 illustrates in side view a layer head of the palletizer of FIG.1.

FIG. 4 illustrates in perspective the layer head of FIG. 3.

FIG. 5 illustrates in perspective a dead plate of the layer head ofFIGS. 3 and 4.

FIG. 6 illustrates separately a submerged bar clamp operating as analternative to the dead plate of FIGS. 3-5.

FIGS. 7-10 illustrate the submerged bar clamp of FIG. 6 as integratedinto a layer head

FIGS. 11-16 illustrate schematically operation of a layer head and thesubmerged bar clamp of FIGS. 6-10.

FIG. 17 illustrates an alternative layer head including a palletizingpuller bar for transferring items onto the layer head.

FIGS. 18-21 illustrate a second form of layer head including a pullerbar and further illustrate a sequence of operation transferring itemsonto the layer head.

FIG. 22 illustrates a drive mechanism for the puller bar of FIGS. 17-21.

FIG. 23 illustrates a stretch wrapper as applied in the context ofconcurrent palletizing and wrapping operations.

FIGS. 24-36 illustrate procedures executed in coordinated palletizingand wrapping operations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates in perspective and FIG. 2 in side view a palletizer10. In FIGS. 1 and 2, palletizer 10 includes a frame 12 of generallybox-form configuration. Frame 12 includes four vertical posts,individually posts 12 a-12 d, supporting an upper structure comprisinghorizontal beams 12 e-12 h. Thus, the lower end of each of posts 12 a-12d rests on a floor and the upper ends of posts 12 a-12 d support beams12 e-12 h. Beams 12 e-12 h provide a generally horizontal rectangularstructure maintained at a given level above floor level. Generally,frame 12 provides a relatively compact overall structure supportingtherein elements of palletizer 10 as described more fully hereafter.

Adjacent frame 12, palletizer 10 includes an infeed conveyor 14. Infeedconveyor 14 is a “production level” conveyor receiving, for example,output from a production or manufacturing operation or from arepackaging operation. Infeed conveyor 14 includes along its length aseries of live, i.e., powered, rollers 14 a. Infeed conveyor 14 alsoincludes a case turner 16. Case turner 16 manipulates incoming items 18,e.g., cases of products, appropriately according to programmed layerbuilding patterns. Use of case turner 16 and layer building methods andpatterns are well known in the art.

Generally, infeed conveyor 14 moves a series of items 18 therealong forpresentation to the remaining portions of palletizer 10 as operatingwithin frame 12. As may be appreciated, infeed conveyor 14 and turner 16operate cooperatively to appropriately orient a sequence of items 18according to a programmed layer building pattern including contemplationof necessary sequential row patterns interfitting to form layer patternsand layer patterns interrelating to produce a stable stack of items on apallet 40. Thus, it will be understood that items 18 are not necessarilysymmetrical and may be oriented according to a specific predefined layerbuilding pattern taking into account row-by-row variations within alayer and layer-to-layer variations for adjacent layers on a stack ofitem 18 layers resting on pallet 40.

Within frame 12, palletizer 10 includes a vertically reciprocating rowconveyor 20 and a vertically reciprocating layer head 22. A row conveyorlift motor 24 when actuated vertically reciprocates conveyor 20 asindicated at reference numeral 21. A layer head motor 26 when actuatedvertically reciprocates layer head 22 as indicated at reference numeral23. Generally, each of row conveyor 20 and layer head 22 areindependently suspended within frame 12. More particularly, row conveyor20 hangs from four suspension points 25. Layer head 22 hangs from foursuspension points 27. Each of conveyor 20 and layer head 22 carry a pairof guides 29. Each of vertical posts 12 a-12 d carry on their innersurface a corresponding guide track 31. Thus, guide tracks 31 on posts12 a and 12 d interfit guides 25 of row conveyor 20 and maintainconveyor 20 along a vertical path within frame 12. Similarly, guidetracks 31 on vertical posts 12 b and 12 c interfit with guides 27 onlayer head 22 to maintain layer head 22 along a vertical path withinframe 12.

Suspension chains and associated sprockets couple each of row conveyor20 and layer head 20 to the respective motors 24 and 26. Moreparticularly, row conveyor 20 hangs within frame 20 from a first set offour suspension chains 32 routed through appropriate sprockets 34 andcoupled to motor 24. Actuation of motor 24 in a first direction lowersrow conveyor 20 and actuation in the opposite direction raises rowconveyor 20. Specifically, the output shaft 24 a of drive motor 24extends the length of horizontal beam 12 e (shown only partially inFIG. 1) and carries at each end a pair of sprockets 34 a. Suspensionchains 36 engage sprockets 34 a and move in response to rotation ofsprockets 34 a. One end of each of chains 32 couples to a suspensionpoint 25 and the other end of each of suspension chains 32 carries acounter weight (not shown) depending directly below each pair ofsprockets 34 a. In this manner, chains 32 remain engaged relative tosprockets 34 a and, therefore, relative to drive motor 24.

Similarly, a second set of four suspension chains 36 and sprockets 38suspend layer head 22 within frame 12 and couple to motor 26. Actuationof motor 26 in a first direction moves layer head 22 upward andactuation in the opposite direction lowers layer head 22. Specifically,the output shaft 26 a of drive motor 26 extends the length of horizontalbeam 12 g (shown only partially in FIG. 1) and carries at each end apair of sprockets 38 a.

Suspension chains 36 engage sprockets 38 a and move in response torotation of sprockets 38 a. One end of each of chains 36 couples to asuspension point 27 and the other end of each of suspension chains 36carries a counter weight (not shown) depending directly below each pairof sprockets 38 a. In this manner, chains 36 remain engaged relative tosprockets 38 a and, therefore, relative to drive motor 26.

Thus, row conveyor 20 and layer head 22 operate independently and may bevertically positioned by appropriately actuating and controlling motors24 and 26, respectively.

Row conveyor 20 moves to a lower position vertically coincident with theheight of infeed conveyor 14 to receive from infeed conveyor 14 one ormore rows of items 18. As discussed above, the items 18 presented to rowconveyor 20 at the output of conveyor 14 correspond to an ongoing layerbuilding pattern, i.e., particular ones of the items 18 within a givenrow are suitably oriented according to and overall sequence of item 18orientation pattern. As live rollers 14 a propel a sequence of items 18onto row conveyor 20, live rollers 20 a activate and collect thesequence of items 18 as a row or rows onto conveyor 20. As may beappreciated, live rollers 20 a are suitably operated in coordinationwith live rollers 14 a of conveyor 14 to pass serially a given set ofitems 18 from conveyor 14 onto conveyor 20. In this manner, conveyor 20receives items 18 from conveyor 14. Conveyor 20 is then verticallypositioned as necessary to vertically coincide with a current height oflayer head 22 to pass items 18 from conveyor 20 to layer head 22.

As may be appreciated, because both row conveyor 20 and layer head 22independently vertically reciprocate a broad combination of relativemovements may be accomplished by programmed control to transfer items 18from conveyor 20 to layer head 22, i.e., one of the two devices may bemoved to match the height of the other or both moved to match someintermediate or predetermined height according to programmed control.Generally, however, it is contemplated that the relatively higher speedconveyer 20 “chase’ layer head 22, i.e., seek out a current height forlayer head 22, when transferring items 18 from conveyor 20 onto layerhead 22. In this particular embodiment, conveyor 20 includes a rowpusher 30 of generally conventional design including a pneumaticcylinder 30 a for pushing a row of items 18 from conveyor 20 onto layerhead 22. Thus, row conveyor 20 vertically aligns itself with a currentvertical position of layer head 22 and passes laterally items 18 fromconveyor 20 to layer head 22.

Generally, layer head 22 tracks the height of a stack of items 18 layeras positioned on a pallet 40. Pallet 40 rests at floor level andreceives layer-by-layer items 18 from layer head 22. Once a completelayer of items 18 has been built on layer head 22, layer head 22deposits the entire layer as a next layer on pallet 40 or on a stack oflayers resting on pallet 40. As will be described more fully hereafter,layer head 22 withdraws its support from below a layer of items 18 anddrops the layer onto a pallet 40 below or onto a stack of item 18 layersresting on pallet 40 below. Layer head 22 then repositions itself, i.e.,raises, to prepare to receive a next item 18 layer from row conveyor 20.

FIGS. 3 and 4 detail layer head 22 as detached from frame 12. FIG. 5illustrates a dead plate 108 of layer head 22, but detached therefromfor purposes of illustration. In FIGS. 3-5, layer head 22 includes a setof free rollers 100 carried on a pair of chains 102 a and 102 b.Sprockets 103 a constrain chain 102 a to an L-shaped path. Similarly,sprockets 103 b restrict chain 102 b to a corresponding L-shaped path.Rollers 100 attach to a length segment of chain 102 a and thereby createa removable floor relative to layer head 22. A drive shaft 105 couplesto one of sprockets 103 a and one of sprockets 103 b and thereby tiestogether chains 102 a and 102 b. Drive motor 104 turns shaft 105 to movechains 102 a and 102 b along their respective and coordinated L-shapedpaths. A pair of vertical plates 110, individually 110 a and 110 b,support shaft 105 and also carry thereacross a stop 111, i.e., a raisededge formation. Stop 111 engages a leading lower edge of an item 18layer while being dropped from layer head 22.

Floor drive motor 104 operates to move chains 102 and thereby withdrawrollers 100 from a supporting or floor position relative to an item 18layer to an open position allowing an item 18 layer to drop throughlayer head 22 onto a pallet 40 therebelow or onto a stack of item 18layers therebelow. Advancing rollers 100 rightward, in the view of FIGS.3 and 4, moves rollers 100 out of a floor position as illustrated inFIG. 4 and into an open position occupying the vertical portion of theL-shaped path provided by sprockets 103 and chains 102. Once the leadingedge of the item 18 layer engages stop 111, the item 18 layer holds itsposition and rollers 100 continue to move out from thereunder to dropthe item 18 layer therebelow. The first row of items 18 to fall fromlayer head 22 is the row most distant from stop 111. Thus, thefirst-to-arrive row of items 18, i.e., the row first placed on layerhead 22 when constructing a layer, is the last row to fall from layerhead 22 when releasing an item 18 layer. The last-to-arrive row is,therefore, the first row dropped from layer head 22. In this manner, acomplete item 18 layer drops through the opened floor of layer head 22.

Layer head 22 includes conditioning mechanisms to better organize agiven item 18 layer thereon prior to dropping the layer on a pallet 40or a stack of layers therebelow. As discussed above, palletizer 10accommodates an ongoing layer building pattern. Items 18 of varyingorientation must be organized into a layer. A relatively loose, i.e.,with space therebetween, initial organization of items 18 betterfacilitates layer building patterns. Thus, as initially organized onlayer head 22, items 18 are loosely packed but possess the requiredrelative orientations to form, when brought together, a desired andcompact overall item 18 configuration within a given layer. Generally,layer head 22 includes conditioning mechanisms to collapse togetheralong orthogonal dimensions a loosely packed item 18 layer into atightly packed item 18 layer.

A pair of side clamps 106, individually 106 a and 106 b, move laterallyinward in a first dimension and compress together an item 18 layer inpreparation for deposit on a stack of item 18 layers therebelow. Apneumatic cylinder 106 c couples by way of scissor mechanism 107 (shownpartially at reference numeral 107 a in FIG. 4) to operate clamps 106 aand 106 b in parallel, i.e., move laterally inward in parallel andcoordinated orientation. A dead plate 108 (shown separately in FIG. 5)rotates about an axis 108 a, i.e. flips up into and past a verticalposition, to compress a layer of items in a second dimension. Thus,operating side clamps 106 and pivoting dead plate 108 compressestogether, in first and second mutually orthogonal dimensions, a layer ofitems 18 prior to deposit on a surface therebelow. Thus, the process ofbuilding a layer row-by-row on lift head 22 results in somedisorganization or loose fitting layers requiring, for optimal stacking,that the layers be compressed together in two dimensions, i.e. squeezedinward by bars 106 and plate 108, to make a compact organized layerready for stacking on a surface therebelow.

In fact, a palletizer which permits significant disorganization in anitem 18 layer while constructing such layer row-by-row promotes rapidconstruction of the layer. For example, certain layer building patternsrequire an interfitting relationship between rows within a layer. Whensuch interfitting is required, it is easier and faster to initially formthe layer as a loose organization of items 18 to better facilitate rowshaving items 18 interfitting with other rows.

Palletizer 10 facilitates such loose organization of a layer of items 18during construction thereof at upward-facing side plates 109 a and 109b. Generally, side plates 109 are upward facing, smooth surfacesadjacent the ends of rollers 100 on each side of layer head 22. Rollers100 are of sufficient length to support a tightly-packed item 18 layerthereon. Rollers 100 need not be any wider than necessary to support anitem 18 layer thereon by virtue of support at side plates 109 a and 109b. More particularly, a loosely fitting item 18 layer occupies morearea, i.e., requires a greater support surface, than a tight-fittingitem 18 layer. Side plates 109 a and 109 b support the outer edges of aloosely-fitting item 18 layer and thereby provide a greater area forsupporting an item 18 layer during construction. In other words, layerhead 22 tolerates significant disorganization among layers during layerformation and thereby facilitates rapid layer construction on layer head22.

Once the layer has been loosely organized on the upward facing surfacesof layer head 22, i.e., on rollers 100 and side plates 109 a and 109 b,dead plate 108 and side clamps 106 operate to drive together andcompress the loosely organized item 18 layer into a tightly fitting item18 layer resting entirely on rollers 100.

As best seen in FIG. 4, the length of dead plate 108 corresponds to thelength of rollers 100. Dead plate 108 includes, at each end, notches 108b and 108 c, respectively. When plate 108 pivots upward, as indicated atreference numeral 108 d in FIG. 5, notches 108 b and 108 c leave an openspace therebelow to accommodate inward movement of clamps 106, i.e.,inward and past the ends of dead plate 108. With dead plate 108 moved toits “clamping” position, i.e., pivoted inward to engage and compress anditem 18 layer resting on layer head 22, side clamps 106 move inward andif necessary reach beyond the ends of rollers 100 to thereby compresstogether in coordination with dead plate 108 an entire item 18 layerfrom a loosely organized item 18 layer into a tightly-fitting item 18layer. As may be appreciated stop 111 operates in coordination withclamps 106 and dead plate 108 to compress together an item 18 layerresting upon layer head 22. More particularly, stop 111 resists movementof an item 18 layer in response to dead plate 108 pivoting into itsclamping position.

In FIG. 5, a pivot shaft 108 g mounts rotatably to layer head 22 andcarries thereon dead plate 108. A pair of pneumatic cylinders 108 ecouple by way of corresponding levers 108 f to pivot shaft 108 g. Thus,actuation of cylinders 108 e causes movement of dead plate 108 between atransition position as shown in FIGS. 4 and 5 and a clamping position,i.e., pivoted inward as indicated at reference numeral 108 g.

Thus, dead plate 108, rollers 100, side plates 109, stop 111 and sideclamps 106 cooperatively tolerate significantly loose organization amongitems 18 when forming an item 18 layer and compress together items 18 ina tight fitting layer supported entirely on rollers 100.

Dead plate 108 provides a transition surface filling a gap between rowconveyor 20 and layer head 22. Conventional dead plates, i.e.,transition devices, are generally fixed in position. Dead plate 100 goesbeyond a transition function and provides a compression function. Thehorizontal position of dead plate 108 provides, therefore, a transitionsurface function when item 18 rows are pushed onto layer head 22. Afterthe last-to-arrive row of items 18 is located on layer head 22, deadplate 108 pivots up to compress and provide a secondary backstop forproper layer construction. Plate 108 thereby provides an ability tolower into a generally horizontal conventional dead plate position for anet fit between a reciprocating layer head 22 and whatever it mates withfor receiving rows, e.g., a row conveyor 20. Pivoting dead plate 108provides also a layer compression device which operates in opposition tostop 111 as provided across plates 110. In other words, dead plate 108can push a layer against the stop 111 and thereby squeeze or compressthe layer between plate 108 and stop 111.

Dead plate 108 provides a particularly important advantage during layerrelease, i.e., when rollers 100 are pulled from under an item 18 layerto drop the item 18 layer through layer head 22. As discussed above,dead plate 108 pivots into clamping or compressing engagement relativeto an item 18 layer to better organize and make compact the item 18layer in preparation for stacking. Leaving dead plate 108 in suchengagement improves release of the first row of items dropped throughlayer head 22. More particularly, and especially with respect to smallerdimensioned items 18, dead plate 108 maintains a given and desiredposition for a row of items 18 when it remains in contact with the rowof items 18 as they fall from of rollers 100 and onto a supportingsurface therebelow. By guiding this first-to-drop row of items 18, deadplate 108 serves an additional guiding function relative to items 18when releasing a row of items 18 from layer head 22. This first-to-droprow of items 18 then serves a similar guiding function relative to anext-to-drop row of items 18. Eventually, the last-to-drop row of items18, i.e., those adjacent stop 111, fall through layer head 22 and findtheir final resting position on pallet 40 or on a stack of item 18layers resting on pallet 40.

Prior art roller floors pulling support from under a layer of itemssuffer from a “loose” row which becomes more troublesome for narroweritem 18 dimensions. In other words, the narrower item 18 is the greaterits tendency to rock out of position when falling from rollers 100. Inaccordance with the present invention, however, dead plate 108 guidesthe first-to-drop item 18 row into position and begins a cascadingseries of supporting elements, i.e., each row is guided into position bythe previous row and the first row is guided into position by dead plate108. In this manner, an item 18 layer compressed together on layer head22 achieves a more stable and better compressed final position afterdropping through layer head 22 as it finds its final resting place onpallet 40 or on a stack of item 18 layers resting on pallet 40.

Compressive forces applied to an item 18 layer by virtue of the item 18layer being captured and compressed between dead plate 108 and stop 111also eliminate a dependence on conventional and undesirably variablecompressive forces supplied by roller floors. In systems using only freerollers pulled from under an item 18 layer, the compressive force, i.e.,against a fixed stop, varies as the roller bearings become more freeturning by the unweighting thereof as items 18 fall therefrom. Forparticularly heavy items 18 and particularly free turning rollers 100,moving rollers 100 out of a supporting position does not generatesignificant compressive forces relative to a load, i.e., the load doesnot bear heavily against a fixed stop under such conditions. Under thepresent invention, however, dead plate 108 maintains static compressionrelative to an item 18 layer regardless of item 18 layer weight anddegree of free-turning characteristic of rollers 100. As a result, anitem 18 layer dropped through layer head 22 enjoys a more compact andbetter organized final resting place on pallet 40 or on a stack of item18 layers resting on pallet 40.

Side plates 109 enhance use of rollers as a floor for a layer conveyor.The span occupied by rollers 100, i.e., as supported at each end thereofat chains 102, is limited by the strength and deflection characteristicsof rollers 100. As may be appreciated, minimizing the length of rollers100 to occupy just sufficient distance to support an entire item 18layer minimizes the cost and structural requirements of rollers 100.Side plates 109 tolerate loose organization within an item 18 layerduring construction thereof. In conventional practice, a forty inch widefinished width for a given item 18 layer requires a roller floor of overfifty inches wide to accommodate the layer during construction. Underthe present invention, however, rollers 100 need only be forty incheswide because side plates 109 support the outer edges of a layer duringconstruction thereof. As the roller floor, i.e., the support provided byrollers 100, width increases, the strength of the rollers must increaseto avoid unacceptable deflection caused by the longer roller length.Increased strength requires increased weight and requires largerdiameter rollers 100 as flooring for layer head 22. Both aspectsnegatively and inefficiently affect machine performance when rollerlength exceeds item 18 layer dimensions. In accordance with the presentinvention, however, rollers 100 are of minimal length just sufficient tosupport a tightly-organized item 18 layer thereon.

Thus, a synchronized palletizer has been shown and described. Thesynchronized palletizer provides a compact overall size with high itemthroughput. Most low infeed, i.e., production level infeed, palletizersrequire a pallet position, a layer build position, and a row buildconveyor. The layer build position is essentially eliminated by buildinglayers on the layer head 22 which also serves also as a layer placementmechanism, i.e., placing item 18 layers on a pallet 40 or stack of item18 layers. This feature is believed to save approximately 25% to 35% ofotherwise required floor space. The synchronized palletizer utilizes arelatively high speed row conveyor to chase down a current position ofthe layer head 22. Generally, conventional layer building brings eachrow to a fixed and maximum height, i.e., above any potential height fora stack of item 18 layers, for each and every row. Each row need only beraised to the height of the current stack level, i.e., to where layerhead 22 is positioned just above pallet 40 or a stack of item 18 layersresting on pallet 40. In this manner, the synchronized palletizerreduces travel distance and travel time for items conveyed to a layerbuilding site.

While illustrated as having two side plates 109, one at each end ofrollers 100, the synchronized palletizer may be operated with only oneside plate 109. The presence of a support area beyond rollers 100 andadjacent thereto facilitates loose packing of item 18 rows duringconstruction of an item 18 layer on layer head 22.

As discussed above, dead plate 108 provides both a compression functionand a guiding function. With respect to compression, dead plate 108engages an item 18 layer and brings together or compresses the layer.With respect to its guiding function, dead plate 108 maintains contactwith the first-to-drop row of items 18 thereby preventing tipping of theitems as the rollers 100 move out from underneath. As discussedhereafter, a back clamp assembly 210 also provides the dual functions ofcompression and guiding during release of items from a layer head.

FIG. 6 separately illustrates back clamp assembly 210 according to anembodiment of the present invention. In FIG. 6, back clamp assembly 210includes a left drive 212 a, a right drive 212 b, and a back clamp bar214. Each of left drive 212 a and right drive 212 b couples to clamp bar214 for reciprocating movement thereof. A synchronizing drive shaft 215also couples together left drive 212 a and right drive 212 b forcoordinated movement thereof. Generally, drives 212 a and 212 b pullclamp bar 214 up from a submerged position, across an item layerbuilding area, and return clamp bar 214 to the submerged position. Aleft side plate 216 a and right side plate 216 b in FIG. 6 arecoincident with a layer building surface 217 supporting a layer 282 ofitems 284 resting on a layer head 280. Drives 212 a and 212 b bringclamp bar 214 from below side plates 216 a and 216 b upward and toward alayer 282 of items 284 as described more fully hereafter. For thepresent discussion, it will be understood that drives 212 a and 212 beach mount upon layer head 280 and side plates 216 a and 216 b form aportion of the layer building surface 217 provided by layer head 280(FIGS. 7-10).

Layer head 280 corresponds generally to layer head 22 as describedabove. Layer head 280, however, includes back clamp assembly 210 asdescribed hereafter in place of dead plate 108. Back clamp assembly 210provides the dual functions of compression and guiding as describedabove with respect to that provided by dead plate 108. Accordingly,layer head 280 will not be described in full detail, it being understoodthat layer head 280 is generally similar to layer head 22 in itsstructure and operation, with the exception that layer head 280 includesback clamp assembly 210 in place of dead plate 108.

Thus, layer head 280 operates within the context of a palletizingoperation wherein successive layers 282 are constructed upon layer head280 and deposited upon a pallet or stack of layers 282 therebelow. Inother words, layers 282 are constructed upon layer head 280 and aredropped through a retractable floor of layer head 280 for deposit upon apallet or stack of layers therebelow.

Left drive 212 a includes a double-ended pneumatic cylinder 220 a. Leftdrive 212 a includes a forward pulley 222 a and a rearward pulley 224 a.A forward coupler 226 a of pneumatic cylinder 220 a couples to a firstend of cable 230 a. A rearward coupler 228 a ties to the other end ofcable 230 a. Cable 230 a routes from coupler 226 a around pulley 222 aand rearward around pulley 224 a to its connection with coupler 228 a.In FIG. 6, coupler 228 a is shown in both its retracted and extendedpositions while coupler 226 a is shown only in its retracted position.It will be understood, however, that during operation of pneumaticcylinder 220 a couplers 226 a and 228 a remain a fixed distance apartwhile reciprocally moving cable 230 a.

Right drive 212 b includes a similar arrangement. More particularly,right drive 212 b includes a pneumatic cylinder 220 b with couplers 226b and 228 b each tied to respective ends of a cable 230 b. Cable 230 bengages pulleys 222 b and 224 b.

With respect to cables 230 a and 230 b, while illustrated schematicallyherein as cables it will be understood that a variety of devices may beemployed to move clamp bar 214. For example, drive belts, chains, andother such devices may be used in conjunction with pulleys 222 a, 222 b,224 a, and 224 b to carry clamp bar 214 along the path described andillustrated herein. In addition to pulleys and such devices as drivebelts, chains, and the like, it will be understood that a variety ofmechanical architectures may be employed to move a clamp bar from asubmerged position into an operating position as described herein.Accordingly, the present invention and any embodiments thereof will notbe limited to the specific cable illustrated and described herein butwill be taken to include other such devices capable of carrying clampbar 214 as described herein.

Thus, when operated in unison pneumatic cylinders 220 a and 220 breciprocate cables 230 a and 230 b together through forward and rearwardmotion. Synchronizing drive shaft 215 ties together pulleys 222 a and222 b and thereby unifies movement of cables 230 a and 230 b. In otherwords, by virtue of synchronizing drive shaft 215 clamp bar 214maintains a given orientation within lift head 280. More particularly,clamp bar 214 remains parallel to the front and rear edges of layer head280. Clamp bar 214 couples to cables 230 a and 230 b. Thus, clamp bar214 follows cables 230 a and 230 b. With this arrangement, clamp bar 214may be positioned below side plates 216 a and 216 b as illustrated inFIG. 6. Activating pneumatic cylinders 220 a and 220 b moves cables 230a and 230 b rearward, i.e., from pulleys 222 a and 222 b toward pulleys224 a and 224 b. This causes back clamp bar 214 to move initially androtationally along the periphery of pulleys 222 a and 222 b andthereafter linearly rearward toward pulleys 224 a and 224 b. As aresult, back clamp bar 214 first resides below side plates 216 a and 216b, but may be brought up and out of this submerged position and to movelinearly and parallel to, but above, side plates 216 a and 216 b.

FIGS. 7 and 8 illustrate back clamp assembly 210 as integrated into lifthead 280. Portions of lift head 280 in the vicinity of right drive 212 bare omitted to better show portions of back clamp assembly 210. In FIG.7, drives 212 a and 212 b have been activated, i.e., pneumatic cylinders220 a and 220 b driven rearward, to position clamp bar 214 most forwardand in its submerged position below side plates 216 a and 216 b (sideplate 216 b being omitted from FIG. 7). FIG. 8 illustrates back clampassembly 210 with pneumatic cylinders 220 a and 220 b driven forward tobring clamp bar 214 up from its submerged position and forward alongside plates 216 a and 216 b (side plate 216 b being omitted from FIG.8). FIGS. 7 and 8 also illustrate a layer 282 of individual items 284.Layer 282 may be constructed or formed upon layer head 280 by pushing orpulling rows of items 284 onto layer head 280. In FIG. 7, with clamp bar214 in its submerged position below side plates 216 a and 216 b, items284 may be pulled or pushed onto layer head 280 directly over clamp bar214. In other words, bar 214 does not obstruct passage of items 284thereover. Once a layer has been formed on layer head 280, back clampassembly 210 may be activated and brought to the position illustrated inFIG. 8 and thereby engage item layer 282.

FIG. 9 illustrates layer head 280 with a layer 282 thereon. In the viewof FIG. 9, most of back clamp assembly 210 is obscured, however, clampbar 214 may be seen in its submerged position below side plates 216 aand 216 b. Layer 282 has been brought onto layer head 280 by, forexample, pushing or pulling items 284 onto a roller floor 285 and sideplates 216 a and 216 b. As described more fully hereafter, roller floor285 retracts from below layer 282 and thereby drops layer 282 throughlayer head 280 for deposit therebelow upon a pallet or stack of layers282.

After a complete layer 282 has been formed upon layer head 280, leftside clamp 286 a and right side clamp 286 b are activated to laterallycollapse layer 280, i.e., push layer 280 off of side plates 216 a and216 b and inward wholly onto roller floor 285. Each of side clamps 286 aand 286 b include a clamp bar 288 a and 288 b, respectively. In theparticular embodiment illustrated herein, clamp bars 288 a and 288 bextend laterally inward and toward one another by means of scissor bars290 a and 290 b, respectively. Each bar 288 a and 288 b is supported ateach end thereof by a block 292. The lower edge of each bar 288 a and288 b is thereby spaced vertically above roller floor 285 and above sideplates 216 a and 216 b sufficient distance to allow passage of clamp bar214 therebetween. In other words, bars 288 a and 288 b operatesufficiently above side plate 216 a and 216 b and roller floor 285whereby clamp bar 214 may be brought out of its submerged position andinto engagement with layer 282 without interference from side clamps 286a and 286 b. In some embodiments, clamp bar 214 can slide directly uponthe upward-facing surface of side plates 216 a and 216 b. Accordingly,operation of clamp bar 214 and operation of side clamps 286 a and 286 bcan occur without interference therebetween.

In FIG. 10, clamp bar 214 has been brought out of its submerged positionand into engagement with layer 282 while side clamps 286 a and 286 b areextended laterally inward without interference therebetween. In thisrespect, clamp bar 214 serves its compression function by operating inconjunction with side clamps 286 a and 286 b and with stop 211 tocompress together laterally and longitudinally inward the items 84 toform a well organized layer 282.

FIGS. 11-16 illustrated schematically the operation of layer head 280including clamp bar 214 as described herein. In FIG. 11, a first layer282 a resides directly below layer head 280. In other words, earlierpalletizing operations formed and deposited layer 282 a upon anotherlayer 282 or a pallet (not shown). Layer head 280 is then positionedjust above layer 282 a to form a next layer 282 b of items 284. Theroller floor 285 together with side plates 216 define the layer buildingsurface 217. Clamp bar 214 resides below layer building surface 217 anditems 284 are pushed or pulled onto surface 217, as indicated atreference numeral 300.

In FIG. 12, a complete layer 282 b has now been formed upon layerbuilding surface 217. This formation process includes laterally inwardcompression by means of side clamps 286 a and 286 b (not illustrated inFIGS. 11-16) and longitudinal compression by means of layer 282 bcaptured between clamp bar 214 and stop 211. Thus, as illustrated inFIG. 12 back clamp assembly 210 has been activated to bring clamp bar214 out of its submerged position below surface 217 and toward stop 211.With layer 282 captured between bar 214 and stop 211, layer 282 islongitudinally compressed.

In FIG. 13, roller floor 285 begins to move out from under layer 282 b.The first-to-drop row 284 a remains in contact with clamp bar 214.Without such contact, the first-to-drop row 284 a can tip off of thetrailing member of roller floor 285 and tip out of the desired layerpattern. In other words, the first-to-drop row 284 a can fall out ofposition as it comes to rest on the layer 282 a therebelow. With clampbar 214 positioned as illustrated in FIG. 13, however, such displacementdoes not occur.

In FIG. 14, the first-to-drop row 284 a has fallen through layer head280 and onto layer 282 a therebelow. Roller floor 285 continues to moveout from under layer 282 c as each successive next-to-drop row of items284 falls through the opening left behind roller floor 285. Eachsuccessive row of items 284 maintains its position by virtue of contactwith the previously dropped row and the next-to-drop row of items 284 a.In other words, each row of items 284 enjoys guiding support as it fallsfrom layer head 280. The first-to-drop row 284 a enjoys support fromclamp bar 214. The last-to-drop row 284 b enjoys support from thepreviously dropped row of items 284 and stop 211. Intervening rows,i.e., rows between the first-to-drop row 284 a and the last-to-drop row284 b enjoy guiding support from surrounding rows of items 284. As aresult, each row of items 284 falling from layer head 280 as rollerfloor 285 moves out from thereunder enjoys guiding support and therebyarrives in a desired position upon a layer of items 284 therebelow orupon a pallet therebelow.

FIG. 15 illustrates complete deposit of layer 282 b upon layer 282 a. Inother words, roller floor 285 has moved completely out from itssupporting position relative to layer 282 b and layer 282 b has fallenthrough the opening left by roller floor 285. Once a layer has been sodeposited, layer head 280 can be repositioned to receive a next layer282.

In FIG. 16, layer head 280 has been moved upward and slightly abovelayer 282 b. Roller floor 285 has been returned to its closed positioncoincident with side plates 216 a and 216 b and layer building surface217, and clamp bar 214 has been returned to its submerged position belowsurface 217. Accordingly, layer head 280 is now ready to receiveadditional items 284 to form a next layer 282 of items 284 upon surface217. Eventually, a sufficient number of layers 282 have been stackedbelow layer head 280 and the stack of layers 282 may be removed.

FIG. 17 illustrates in perspective a layer head 380. Layer head 380 isgenerally similar to layer head 22 and layer head 280, but includes apuller bar assembly 382. Puller bar assembly 382 provides a transferfunction pulling a row or rows of items 18 onto layer head 380. Forexample, puller bar assembly 382 replaces row pusher 30 (FIG. 1) asapplied in the context of the palletizer 10. It will be understood,however, that layer head 380 need not be used in the specific context ofpalletizer 10 and may be applied in a variety of palletizing anddepalletizing operations. Generally, puller bar assembly 382 includes apuller bar 384 positionable in its extended position as indicated inFIG. 17. By positioning a row or rows of items 18 between puller bar 384and layer head 380 and moving puller bar 384 to its retracted positionsas described more fully hereafter, a row or rows of items 18 may betransferred onto layer head 380. Thus, puller bar assembly 382reciprocates puller bar 384 between an extended and retracted positionas indicated by referenced numeral 386 in FIG. 17.

Puller bar 384 moves in a plane located just above roller floor 385 andside plates 316 of layer head 380. Puller bar assembly 382 includes aleft slide 390 and a right slide 392. As described more fully hereafter,slides 390 and 392 move slidably relative to layer head 380 in thereciprocating directions indicated at reference numeral 386 in FIG. 17.Extending upward from slide 90, puller bar assembly 382 includes a leftear 394 and extending upward from slide 392 a right ear 396.Accordingly, ears 394 and 396 move reciprocally with slides 390 and 392,respectively. A tie bar 398 couples ears 394 and 396. Tie bar 398 islocated sufficient distance above roller floor 385 and side plates 316to accommodate passage of items 18 thereunder. In other words, tie bar398 operates above a row or rows of items 18 and above a layer of items18 as constructed upon layer head 380. An L-shaped left support arm 400and an L-shaped right support arm 402 couple tie bar 398 and puller bar384. In other words, arms 400 and 402 support puller bar 384 within aplane just above roller floor 385 and side plates 316. As a result, tiebar 398 and support arms 400 and 402 move above a row or rows of items18 and a layer of items 18 as positioned on roller floor 385 and sideplates 316.

With puller bar 384 in its extended position as indicated in FIG. 17,tie bar 398, support arms 400 and 402, and puller bar 384 accommodateentry of a row or rows of items 18 along a path generally parallel topuller bar 384 and intermediate puller bar 384 and layer head 380, e.g.,as indicated at reference numeral 404 of FIG. 17. In other words, thearchitecture of puller bar 384 as shown in FIG. 17 accommodatespositioning of a row or rows of items 18 by movement along a line oftravel as indicated at reference numeral 404. Once positioned betweenpuller bar 384 and layer head 380, puller bar 384 moves to its retractedposition, i.e., toward layer head 380 and above roller floor 385, toposition a row or rows of items 18 upon layer head 380.

In the alternative, a row or rows of items 18 may be brought verticallyupward into position between the extended puller bar 384 and layer head380 as indicated at reference numeral 406 in FIG. 17. For example, asapplied in the context of the synchronized palletizer 10 of FIG. 1, arow or rows of items 18 located on row conveyor 20 may be broughtvertically upward in relation to layer head 380 as indicated atreference numeral 406 and thereby positioned between puller bar 384 andlayer head 380. As may be appreciated, such vertical movement of a rowor rows of items 18 as indicated at reference numeral 406 may beaccomplished by relative movement between row conveyor 20 and layer head380.

FIG. 18 illustrates an alternative layer head 380′ similar to layer head380, but including an alternative form of puller bar assembly, i.e.,puller bar assembly 382′. Puller bar assembly 382′ includes slides 390and 392, ears 394 and 396 and tie bar 398. Puller bar assembly 382′ alsoincludes a puller bar 384 moving between an extended and retractedposition just above the plane of roller floor 385 and side plates 316.Assembly 382′ differs from assembly 382 in that support arms 400′ and402′ attach at slides 390 and 392 and extend horizontally toward andjust above puller bar 384. A cross bar 403 couples arms 400′ and 402′and supports directly therebelow puller bar 384. Arm 400′ pivotallycouples at pivot pin 406 relative to slider 390 and arm 402′ pivotallycouples at pivot pin 408 relative to slider 390. Generally, puller barassembly 382′ accommodates vertical movement of a row or rows of items18 into position between puller bar 384 and layer head 380′. Pivotallymounting arms 400′ and 402′ allows movement of arms 400′ and 402′together with puller bar 384 should an undesired or unintended collisionoccur during such relative vertical movement of a row or rows of items18 into position between puller bar 384 and layer head 380′. Forexample, as applied in the context of a palletizer 10 row conveyor 20moves a row or rows of items 18 resting thereon into position betweenpuller bar 384 and layer head 380′ by relative vertical movement betweenconveyor 20 and layer head 380′. During such relative vertical movement,unintended collision could occur, e.g., by virtue of a misplace item 18,and free pivotal mounting of puller bar 384 avoids damage to the item 18or to the palletizing equipment.

FIGS. 18-21 illustrate use of layer head 380′ in the context ofpalletizer 10. It will be understood, however, that layer head 380′ maybe used in a variety of palletizing and depalletizing operations apartfrom the specific synchronized palletizer 10. In FIG. 18, a row of items18 reside upon row conveyor 20. Row conveyor 20 moves relative to layerhead 380′ as indicated at reference numeral 406 with puller bar 384 inits extended position. In other words, layer head 380′ may be movedvertically downward relative to conveyor 20, conveyor 20 may be movedvertically upward relative to layer head 380′ or a combination ofvertically downward movement for layer head 380′ and vertically upwardmovement for conveyor 20 may occur to position the row or rows of items18 between puller bar 384 and layer head 380′.

FIG. 19 illustrates the coordinated positioning of conveyor 20 and layerhead 380′ with a row or rows of items 18 positioned between puller bar384 and layer head 380′. In such position, puller bar 384 is retractedinward toward layer head 380′ to engage the row or rows of items 18 atpuller bar 384 and move the row or rows of items 18 onto roller floor385 and, possibly, side plates 316.

FIG. 20 illustrates movement of puller bar 384 inward as indicated atreference numeral 410 toward and over roller floor 385 and side plates316. Puller bar 384 travels sufficient distance to bring the row or rowsof items 18 onto roller floor 385 and side plates 316 as shown in FIG.20. Thus, the first row or rows of items 18 pulled onto layer head 380′,occupy a position as indicated in FIG. 20. Subsequent row or rows ofitems 18 pulled onto layer head 380 urge prior rows of items 18 furtheronto layer head 380.

FIG. 21 illustrates layer head 380′ following such subsequent placementof rows of items 18 on layer head 380′. For each new row pushed ontolayer head 380′, earlier rows of items 18 are urged further onto layerhead 380′. Eventually, a complete layer of items 18 is formed on layerhead 380′. Side clamps 420 urge the layer of items 18 laterally inwardwhile puller bar 384 pushes the layer of items 18 against stop 311. As aresult, the layer of items 18 is collapsed inward laterally and betweenpuller bar 384 and stop 311. A fully collapsed layer of items 18 resultsand occupies a position on roller floor 385. As described above forlayer head 22, roller floor 385 may be retracted with movement thereoftowards stop 311 to drop the layer of items 18 vertically downwardthrough layer head 380′. As with dead plate 108 and submerged clamp bar215, puller bar 384 provides an “anti-tipping” function with respect tothe first-to-drop row of items 18. In other words, puller bar 384 servesa similar function as that depicted with respect to submerged clamp bar214 in FIGS. 11-16 to promote a well organized layer of items 18 asdeposited below layer head 380′.

Thus, puller bar 384 provides a transfer function pulling a row or rowsof items 18 onto a layer head, a compression function to collapse andbetter organize a layer of items 18 upon a layer head, and an“anti-tipping” function when retracting a roller floor to deposit alayer of items 18 through a retractable floor of a layer head.

FIG. 22 illustrates a drive mechanism 450 applicable to the puller barassemblies 382 and 382′ as described herein above. Drive mechanism 450includes a drive motor 452 coupled by worm gear (not shown) to a driveshaft 454. Drive shaft 454 mounts rotatably relative to layer head 380and/or 380′ at drive shaft bearings 456. Drive shaft 454 carries a leftdrive pulley 460 and a right drive pulley 462. Rotatably mounted tolayer head 380 and/or layer head 380′, a left idle pulley set 461couples by chain 465 to left drive pulley 460. A right idle pulley set463 couples by chain 467 to right idle pulley 462. Thus, operation ofdrive motor 452 in a first direction drives chains 465 and 467 in afirst rotational direction while operation of drive motor 452 in anopposite direction moves chains 465 and 467 in an opposite rotationaldirection. Left slide 390 couples to chain 465 and right slide 392couples to right chain 467. Drive motor 452 thereby reciprocates slides390 and 392 as indicated at reference 386 in FIG. 17. FIG. 22 showspuller bar 384 in its extended position. In phantom, FIG. 22 showspuller bar 384 in its retracted position.

The illustrated puller bar, being mounted upon a verticallyreciprocating layer head with layer building platform, improves overallpalletizing operations. For example, once a row or rows of items 18 havebeen engaged by puller bar 384 and have been positioned sufficientlyonto the layer head, a structure previously supporting the row or rowsof items 18, e.g., conveyor 20 in the example of palletizer 10, may bewithdrawn relative to the layer head. In other words, a row or rows ofitems 18 positioned between puller bar 384 and layer head 380 or 380′need be only partially taken onto the layer head 380 or 380′, e.g.,sufficiently to support the row or rows of items 18 thereon, andconveyor 20 may be withdrawn immediately without waiting for fullytransferring the row or rows of items 18 onto layer head 380 or 380′.Overall palletizing operations thereby improve by speeding the transferof items 18 from conveyor 20 to layer head 380 or 380′. Thus, in avertically reciprocating layer head including a layer building platform,mounting a puller bar thereon improves item transfer time from aseparate device positioning the row or rows of items in relation to thepuller bar.

FIG. 23 illustrates a stretch wrapper 500. Stretch wrapper 500 may beincorporated into a variety of palletizing operations. It will beunderstood, therefore, that stretch wrapper 500 is not limited to theparticular palletizing context illustrated herein. Thus, FIG. 23illustrates a pallet 40 and it will be understood that a palletizer,e.g., synchronized palletizer 10, stacks layers of items 18 upon pallet40. As integrated into synchronized palletizer 10 pallet 40 of FIG. 23is located in a position corresponding to that indicated in FIG. 1. Inother words, pallet 40 of FIG. 23 is located in such position relativeto a palletizing machine to receive sequentially layers of items 18thereon. It will be understood, therefore, that any given palletizingoperation may be employed in combination with stretch wrapper 500 wherelayers of items 18 are deposited upon a pallet 40 or other similarsupport structure to build a stack of item 18 layers thereupon.

Stretch wrapper 500 includes a pallet turntable 502 and a stretch wrapdispenser 504. Stretch wrapper 500 operates under a programmable control506 illustrated schematically in FIG. 23. As may be appreciated, control506 orchestrates operation of stretch wrapper 500 as describedhereafter. Control 506 also controls a corresponding palletizer devicefor coordinated operation thereof, e.g., coordinating stretch wrapper500 procedures with deposit of item 18 layers upon pallet 40 or uponpreviously deposited layers of items 18. For example, control 506coordinates operation of palletizer 10 with operation of stretch wrapper500.

Turntable 502 selectively rotates in a clockwise direction 508 and acounter clockwise direction 510. Turntable 502 also includes a set ofselectively powered rollers 512 and associated stationary peripheralsupport rollers 514. As may be appreciated, powered rollers 512 may beselectively operated in first and second directions to move a pallet 40resting thereon in corresponding first and second directions transverseto rollers 512. Accordingly, pallet 40 may be brought onto table 502 byan associated conveyance (not shown) and positioned selectively uponturntable 502 at a given angular orientation. By aligning power rollers512 transverse to a selected approach path for pallet 40 a leading edgeof pallet 40 may be engaged by rollers 512 to bring pallet 40 ontoturntable 502. Thereafter, pallet 40, and any items 18 stackedthereupon, may be rotated selectively in clockwise direction 508 orcounterclockwise direction 510. As will be described more fullyhereafter, rotating pallet 40 with items 18 stacked thereon whileconcurrently dispensing stretch wrap film from wrapper 500 accomplishescoordinated palletizing operations and stretch wrapping operations. Oncepallet 40 has received a stack of items 18 and the stack of items 18have been suitably wrapped, the assembly can be taken from turntable 502by suitably orienting, e.g., by clockwise rotation 508 orcounterclockwise rotation 510, rollers 512 transverse to a selected exitpath. Power rollers 512 may then be activated to move pallet 40 and itsassociated wrapped stack of items 18 along the selected exit path fromturntable 502 and onto an associated exit conveyance (not shown).

Dispenser 504 includes a vertically disposed tower 520. A film carriage522 reciprocates vertically upon tower 520 as indicated at referencenumeral 523. Carriage 522 includes a roll of stretch film 524 and a setof pre-stretch rollers 526 as known in the art. Pre-stretch rollers 526partially stretch film 524 whereby film 524 thereafter contractsslightly and better engages a stack of items 18 once encircled thereby.There are, however, a variety of mechanisms and methods available in theart for pre-stretching stretch film 524. For example, the roll of film524 may be braked or offer resistance against dispensing therefrom andthereby stretch film 524 as it is wrapped about a load. In some cases,film 524 need not be stretched. Accordingly, the present invention shallnot necessarily be limited to use of the pre-stretch rollers 526.Generally, pre-stretch rollers 526 operate as a set of rollers pinchingfilm 524 therebetween with a down stream roller set operating at aslightly greater speed relative to upstream roller set.

Carriage 522 further includes a selectively positionable gripping andcutting arm 530. Arm 530 pivots about a vertical axis 534. A pneumaticcylinder 532 couples carriage 522 and arm 530 to accomplish pivotingmovement of arm 530. The distal end of arm 530 carries a verticallydisposed arm 531. Arm 531 carries a clamp cylinder 540, a pivotallymounted clamp 542, and a hot wire film cutter 544. While a particularform of film cutter is illustrated herein, i.e., a hot wire film cutter544, it will be understood that a variety of film 524 cutting devicesmay be used. Accordingly, the present invention shall not be limited toa particular form of film 524 cutter. Clamp 542 pivots at the distal endof arm 531 under influence of cylinder 540. A foot 546 of clamp 542thereby pivots into arm 531 in its closed position and away from arm 531in its open position. As described more fully hereafter, selectiveoperation of cylinder 540 opens and closes clamp 542 whereby a loweredge of film 524 may be captured between foot 546 and arm 531.

Turntable 502 includes a linear clamp 550. Thus, clamp 550 includes apair of clamp feet 552 and 554 moveable in linear fashion relative toone another to selectively open and close clamp 550. Clamp 550 residesupon turntable 502. Clamp 550 thereby rotates in clockwise direction 508and counterclockwise direction 510 along with turntable 502. Coordinatedoperation of arm 530 and clamps 542 and 550 permit carriage 522 to passa distal end of film 524 from clamp 542 to clamp 550. For example, withthe distal end of film 524 engaged by clamp 542, arm 530 may be swunginto suitable position relative to clamp 550 to position an edge of film524 within the feet 552 and 554 of clamp 550. Closing clamp 550 andsubsequently opening clamp 542 accomplishes a “hand off’ of film 524from clamp 542 to clamp 550.

Accordingly, it will be understood that control 506 may be programmed toaccomplish a variety of procedures relative to wrapper 500.

A CARRIAGE UP procedure moves carriage 522 vertically upward along tower520. As may be appreciated, carriage 522 enjoys a range of travelsufficiently high to position film 524 at the top layer of a stack ofitems 18 resting on pallet 40.

A CARRIAGE DOWN procedure moves carriage 522 vertically downward alongtower 520. As may be appreciated, carriage 522 may be moved sufficientlylow enough to pass film 524 from clamp 542 to clamp 550.

Accordingly, it will be understood that carriage 522 may be selectivelypositioned along tower 520 between a lower-most position sufficientlylow to pass film from clamp 542 to clamp 550 and sufficiently highenough to wrap film 524 around a stack of items 18 resting upon pallet40.

A ROTATE CLOCKWISE procedure occurs by operation of turntable 502 in theclockwise direction 508. Similarly, a ROTATE COUNTERCLOCKWISE procedureoccurs by rotation of turntable 502 in the counterclockwise direction510. Thus, turntable 502 may be positioned at a selected angularorientation to accomplish a variety of tasks. For example, turntable 502may be selectively positioned to receive a pallet 40 along an approachpath or to eject pallet 40 along an exit path. Generally, whencoordinating palletizing and wrapping operations, an empty pallet 40 isbrought onto turntable 502 and a loaded pallet 40, i.e., holding a stackof items 18 thereon, exits turntable 502. It will be understood,however, that wrapper 500 could be used apart from wrapper operationswherein a loaded pallet 40 may be brought onto turntable 502. With film524 engaged at clamp 550 or otherwise attached to a load of items 18,rotating turntable 502, e.g., in the clockwise direction 508, dispensesfilm 524 and wraps film 524 about the load.

A SWING IN procedure activates cylinder 532 to bring arm 530 towardturntable 502. A SWING OUT procedure occurs by actuating cylinder 530 inan opposite direction to move arm 530 away from turntable 502.

An ARM CLAMP OPEN procedure occurs by activating cylinder 540 to pivotclamp 542 in such direction to move foot 546 away from arm 531. An ARMCLAMP CLOSE procedure occurs by actuating cylinder 544 in an oppositedirection to bring food 546 against arm 541.

A TURNTABLE CLAMP CLOSE procedure occurs by actuating clamp 550 to bringclamp feet 552 and 554 together. A TURNTABLE CLAMP OPEN procedure occursby bringing clamp feet 552 and 554 away from one another.

A ENERGIZE CUTTER procedure occurs by suitably positioning film 524against hot wire cutter 544 and actuating cutter 544, e.g., passingelectrical current therethrough to elevate the temperature of cutter 544and thereby sever film 524.

A DROP LAYER procedure may be executed by coordinated operation of anassociated palletizing device. For example, synchronized palletizer 10may be operated to bring a layer of items 18 onto pallet 40 or onto apreviously deposited layer of items 18. In other words, the DROP LAYERprocedure brings a layer of items 18 onto pallet 40 or a stack of items18 resting thereon.

In a LAYER BUILD procedure rows of items are accumulated onto a layerbuild platform. This process occurs concurrently, but independent ofstretch wrap operations.

A TURNTABLE HOME procedure rotates turntable 502 to place turntableclamp 550 as indicated in FIG. 23, i.e., in position to interact withclamp 542. Typically, the direction of rotation would be along clockwiserotation 508 as such rotation corresponds with rotation executed forfilm 524 wrapping as described more fully hereafter.

A PALLET MOVE procedure activates power rollers 512 according to adesired direction of travel for a pallet 40 to accomplish or exit of apallet 40 and/or load of items 18 resting thereon.

An EMPTY PALLET ENTRY procedure begins with a ROTATE CLOCKWISE procedureor a ROTATE COUNTERCLOCKWISE procedure to align turntable 502 suitablywith an approach path relative to a pallet conveyor infeed device. Next,a PALLET MOVE procedure is executed to draw the empty pallet 40 from theinfeed conveyor onto turntable 502.

A PALLET POSITION procedure is used to appropriately position a pallet40 for row push direction. A ROTATE CLOCKWISE procedure or a ROTATECOUNTERCLOCKWISE procedure is executed to suitably align a pallet 40along its forty inch dimension or along its forty eight inch dimensionwith the desired orientation for a DROP LAYER procedure. In other words,turntable 502 is suitably oriented to receive a next layer of items 18according to a particular stacking pattern.

A DEPOSIT LAYER procedure begins with turntable 502 pre-positioned toreceive a next layer of items 18. In other words, before receiving alayer of items 18, turntable 502 is positioned suitably according to aparticular stacking pattern. Following such positioning, a DROP LAYERprocedure maybe executed to bring a next layer of items 18 into wrapper500.

A START WRAP procedure begins with one or more DEPOSIT LAYER procedures.In other words, wrapping a load is typically preceded by one or moreunwrapped layers of items 18 begin deposited. If necessary, a ROTATECLOCKWISE procedure or a ROTATE COUNTERCLOCKWISE procedure is executedto align clamp 550 with tower 520. In other words, turntable 502 isbrought to its home position in preparation for handing film 524 fromclamp 542 to clamp 550. Next, a TURNTABLE CLAMP OPEN procedure isexecuted to prepare clamp 550 receiving film 524. A SWING IN procedureis executed to bring clamp 542 into vertical alignment with clamp 550. ACARRIAGE DOWN procedure is then executed to lower film 524 into clamp550. Next, a TURNTABLE CLAMP CLOSE procedure is executed to grip thelower edge of film 524 at clamp 550. With film 524 so engaged at clamp550, an ARM CLAMP OPEN procedure is executed to release film 524relative to carriage 522. This allows a SWING OUT procedure to occurwhereby clamp 542 is taken out of vertical alignment with clamp 550.Next, a ROTATE CLOCKWISE procedure occurs to begin pulling film 524 fromcarriage 522 and thereby begin wrapping film 524 about items 18.Following completion of approximately one revolution of table 502, aTURNTABLE CLAMP OPEN procedure may be executed to release film 524 fromclamp 550. As the ROTATE CLOCKWISE procedure continues, a CARRIAGE UPprocedure is executed at a suitable rate to achieve a desired filmoverwrap. In other words, coordinated upward movement of carriage 522occurs along with clockwise rotation of turntable 502 to suitably wrap aload of items 18.

An INTERMEDIATE WRAP procedure begins after one or more DROP LAYERprocedures have occurred. In other words, in support of coordinatedpalletizing and wrapping operations after one or more layers of items 18have been deposited, the INTERMEDIATE WRAP procedure is initiated towrap such newly deposited layers of items 18. Because film 524 isalready engaged or encircled about the previously deposited layers ofitems 18, a ROTATE CLOCKWISE procedure is executed to further encirclefilm 524 about the load, i.e., to wrap the newly deposited layers ofitems 18. In coordination with the ROTATE CLOCKWISE procedure, aCARRIAGE UP procedure is executed at a rate necessary to achieve adesired film overwrap. The ROTATE CLOCKWISE procedure terminates whenthe newly deposited layers of items 18 have been suitably wrapped andwhen turntable 502 is positioned to receive additional layers of items18.

A FINAL WRAP procedure occurs following a FINAL DROP LAYER procedure. Inother words, once the final layer of items 18 have been deposited, thewrapping process can be terminated. A ROTATE CLOCKWISE procedureexecutes to encircle the final layer of items 18. A CARRIAGE UPprocedure is executed at a suitable rate to achieve desired film 524overwrap until the film is located at the top of the load of items 18.The ROTATE CLOCKWISE procedure terminates when the turntable ispositioned to align with a discharge conveyor. In other words, rotationcontinues until the power rollers 512 are aligned transverse to an exitpath. A SWING IN procedure is then executed in coordination with an ARMCLAMP OPEN procedure to bring clamp 542 into position to engage anintermediate portion of film 524, i.e., a portion between the load ofitems 18 and pre-stretch rollers 526. A CARRIAGE DOWN procedure isexecuted to increase the “rope” of film 524 in the clamp area of clamp542. An ARM CLAMP CLOSE procedure is then executed to capture the“roped” portion of film 524 in clamp 542. Thereafter, an ENERGIZE CUTTERprocedure is executed to sever film 524 between clamp 524 and the loadof items 18. With film 524 so severed, a SWING OUT procedure is executedto clear arm 530 relative to the load of items 18 in preparation fordischarging the load from wrapper 500.

A DISCHARGE PALLET procedure begins with a PALLET MOVE procedure to movepallet 40 and its associated load of items 18 along a selected exitpath. If necessary to align turntable 502 to receive a next emptypallet, a ROTATE CLOCKWISE procedure or a ROTATE COUNTERCLOCKWISEprocedure is then executed. A CARRIAGE DOWN procedure may be thenexecuted to position carriage 522 at an elevation for transfer of film524 to turntable clamp 550.

For purposes of clarity in the illustrations, film 524 will not beillustrated in its extended positions from the roll of film 524 uponcarriage 522 and toward and about items 18. It will be understood,however, that film 524 is pulled from the roll of film 524 by engagingfilm 524 initially at clamp 550 and rotating turn table 502 in theclockwise direction 508. By coordinating rotation of turntable 502 withvertical movement of carriage 522, helical wrapping of film 524 about aload of items 18 resting upon pallet 40 occurs. Generally, during suchwrapping operations film 524 extends from pre-stretch rollers 526outward, bypassing arm 530, and engaging either clamp 550 or a load ofitems 18 resting upon pallet 40. During cutting or transfer operations,however, arm 530 engages film 524 in the portion of film 524intermediate pre-stretch rollers 526 and a wrapped load of items 18 inthe case of a cutting procedure and a portion of film 524 intermediateclamp 542 and pre-stretch rollers 526 in the case of a film transferoperation.

For purposes of illustration a standard pallet is depicted for buildingload thereupon. Loads without pallets or loads build on slip sheets areequally valid using the teachings in this disclosure.

FIG. 23 illustrates an empty pallet 40 positioned upon turntable 502with film 524 gripped in clamp 542. Wrapper 500 is now prepared toreceive items 18, i.e., from an associated palletizing operationdepositing layers of items 18 upon pallet 40 or upon previouslydeposited layers of items 18. Also in FIG. 23, turntable clamp 550 is inposition aligned for interaction with arm clamp 542. Turntable clamp 550need not, however, necessarily be aligned relative to arm clamp 542 whenreceiving pallet 40 or during initial stacking of items 18 thereon.Alignment of clamps 542 and 550 occurs at the commencement of wrappingprocedures, i.e., when a distal end of film 524 is transferred fromclamp 542 to clamp 550 when turntable 502 is in its “home” position asillustrated in FIG. 23. Thus, pallet 40 as illustrated in FIG. 23 may betaken onto turntable 502 from a variety of approach paths.

FIG. 24 illustrates a partial or full load of items 18 received uponpallet 40. Generally, wrapping occurs once a partial item 18 load isreceived, but some short loads may have all stretch wrapping occur afterload completion. In FIG. 24, arm 531 has been moved inward towardturntable 502 with clamp 542 in alignment with clamp 550. In otherwords, aligned for film 524 transfer from clamp 542 to clamp 550.Carriage 522 lowers film 524 into clamp 550 and clamp 550 engages film524. Thereafter, clamp 542 may be deactivated whereupon rotation ofturntable 502 in a clockwise direction 508 begins wrapping of film 524about the load of items 18.

FIG. 25 illustrates clamp 542 having opened after transfer of film 524to clamp 550. Once film 524 has been transferred to clamp 550, arm clamp542 returns to its retracted position allowing turntable 502 rotation insupport of wrapping procedures.

FIG. 26 illustrates turntable 502 rotating in the clockwise direction508 for stretch wrapping of the partial load of items 18 as stacked uponpallet 40. Thus, a partial load of items 18 may be wrapped according toembodiments of the present invention without necessarily stacking anentire load of items 18. After wrapping the partial load, additionallayers of items 18 may be added as described hereafter. In other words,additional layers are deposited upon previously deposited layers withturntable 502 suitably oriented to receive such additional layers. Whiledescribed herein as occurring just prior to a wrapping procedure, filmtransfer from clamp 542 to clamp 550 can occur at a variety of times.For example, film transfer can occur before an empty pallet 40 arrivesat turntable 502, when an empty pallet 40 is in position upon turntable502, after deposit of a partial load of items 18, or after completion ofdeposit of a full load of items 18.

FIG. 27 illustrates a complete load of items 18 stacked upon pallet 40.As shown in FIG. 27, carriage 522 has been moved vertically upward incoordination with stacking operations, i.e., deposit of layers of items18, whereby ongoing wrapping occurs by coordinated positioning ofcarriage 522 and rotation of turntable 502. Once the load of items 18has been completed, turntable 502 may be moved to its home position asindicated in FIG. 27.

FIG. 28 illustrates severing or cutting of film 524. Arm 530 moves intoits extended position as indicated at FIG. 28 and engages film 524.Carriage 522 is then moved slightly vertically upward to gather togethera portion of the lower edge or lower portion of film 524 at clamp 542.This establishes a desirable “roping” effect whereby a portion of film524 is collected together and captured within clamp 542, i.e., betweenfoot 546 and arm 531. Once suitably engaged within clamp 542, cutter 544may be energized thereby severing film 524 at a point between clamp 542and the wrapped load of items 18. As may be appreciated, the distal endof film 524, relative to carriage 522, remains gripped at clamp 542 andmay be subsequently transferred to turntable clamp 550 in support offurther wrapping operations. Once the last layer of items 18 has beenplaced, a final wrap cycle occurs, including such cutting procedures, toreduce the time of stretch wrapping and thereby allow faster emptypallet change out procedures.

FIG. 29 shows the load of items 18 exiting turntable 502 with arm 530retracted and film 524 gripped at an upper level where film cuttingpreviously occurred. Thus, once arm 530 has been retracted and a cuttingprocedure executed, power rollers 512 are actuated as indicated atreference 570 to move the pallet 40 and load of items 18 resting thereonalong an exit path 572. Wrapper 500 is then ready to receive a nextempty pallet 40 in support of continued cooperative palletizing andwrapping operations.

FIG. 30 illustrates pallet 40 entering with turntable clamp 550 notaligned with dispenser 504, i.e., with turntable 502 not in its homeposition as indicated in FIG. 23. Thus, power rollers 512 are actuatedat reference numeral 574 and pallet 40 approached turntable 502 along anapproach path 576. Embodiments of the present invention do notnecessarily require that turntable 502 be rotated to its home positionwhen receiving a pallet 40. This flexibility in turntable position atthe time of receiving an empty pallet 40 benefits palletizingoperations. For example, some loads of items 18 benefit from pushingforty inch rows and others benefit from pushing forty eight inch rows ofa standard forty inch by forty eight inch pallet. Because film 524transfer from clamp 542 to clamp 550 need not occur until after items 18are deposited, improved optimization of load build, i.e., palletizing,can occur without compromising film transfer or attachment relative toturntable 502 or a load of items 18 resting upon pallet 40. Thus,allowing an empty pallet 40 to enter with turntable 502 in other thanits home position facilitates optimized palletizing procedures, butavoids undesirable collisions with the incoming empty pallet 40 if thefilm were to remain attached to turntable 502 at clamp 550.

Turntable film clamp 550 need not be aligned with the stretch wrapperupon pallet entry or palletizing procedures. After a pallet 40 entersturntable 502, pallet 40 can be rotated to a position that maximizespalletizing operations independent of both the turntable clamp 550 andstretch wrapper 500. After layers are deposited and wrapping commences,the load can be rotated to align the turntable clamp 550 and stretchwrapper 500.

FIG. 31 illustrates a load of items 18 partially built upon pallet 40with turntable 502 in its non-home position, i.e., as positioned forreceiving the empty pallet 40 as indicated in FIG. 30.

FIG. 32 illustrates turntable 502 having rotated to align turntableclamp 550 with arm clamp 542. Arm 530 may then be actuated to move intoalignment with clamp 550, carriage 522 lowered to bring film 524 intoposition between feet 552 and 554 of clamp 550 clamp 550 activated toengage the lower edge of film 524, and clamp 542 opened to release film524 and thereby “pass” or transfer film 524 from clamp 542 to clamp 550in preparation for commencing wrapping operations.

In FIG. 33, wrapping operations commence by rotation of turntable 502,e.g., clockwise in the view of FIG. 33, to encircle the load or partialload of items 18 with film 524. As may be appreciated, in conjunctionwith rotation of turntable 502 carriage 522 move vertically upward toestablish a helical path about the load of items 18 or partial load ofitems 18. As may be appreciated, wrapping procedures are coordinatedwith palletizing procedures whereby one or more layers of items 18 maybe deposited and wrapping procedures occur relative to such newlydeposited items 18. For example, FIG. 34 illustrates orientation oftable 502 suitably to receive a next layer of items 18. This next layerof items 18 may be wrapped by rotation of turntable 502, or additionallayers of items 18 may be deposited as desired. As illustrated in FIG.35, eventually a complete load of items 18 are stacked upon pallet 40and a film cut procedure occurs whereby arm 530 swings into positionwith clamp 542 in its open position. Thereafter, upward movement ofcarriage 522 gathers together or “ropes” the lower edge of film 524 andclamp 542 is activated to secure film 524 relative to carriage 522.Cutter 544 is then activated to sever film 524 between clamp 542 and thewrapped load of items 18. FIG. 36 illustrates exit of the wrapped loadof items 18 relative to turntable 502 along a selected exit path 578 byactivating power rollers 512 as indicated at reference numeral 580. Inthe illustrated example, the exit path 578 aligns with the entrance path576 as indicated in FIG. 30. It will be appreciated, however, that anyselected exit path could be chosen depending on the surroundingenvironment, i.e., particular conveyances employed to bring pallets 40into wrapper 500 and to eject loaded pallets 40 from wrapper 500. Thus,FIG. 36 illustrates a load of items 18 exiting wrapper 500 after arm 530has retracted and a film cut cycle has occurred independent of turntableclamp 550 position.

It will be appreciated that the present invention is not restricted tothe particular embodiment that has been described and illustrated, andthat variations may be made therein without departing from the scope ofthe invention as found in the appended claims and equivalents thereof.

1. A method of arranging plural items on a pallet using a palletizerhaving a frame and a delivery device for delivering said items to thepalletizer at a delivery height, comprising the steps of: a. deliveringitems to the palletizer at the delivery height; b. vertically moving anaccumulator to a position at which said accumulator is capable ofreceiving said items transferred from said delivery height; c.transferring said items onto the accumulator; d. raising the accumulatorto a level at which an edge of said accumulator is coincident with anedge of a layer head edge, said layer head having a puller bar mountedto said layer head and a layer head floor movable between a closedposition and an open position; e. with the layer head floor in theclosed position, horizontally moving the puller bar without horizontalmovement of said layer head to horizontally transfer said items from theaccumulator onto the layer head floor until at least some of said itemsabut a layer head stop, and clamping said items between said puller barand said stop; f. vertically moving the layer head to an elevationimmediately above an item deposit level; and g. moving said layer headfloor to the open position to deposit said items at the item depositlevel.